This is Dremel's 1/8" Carbon Steel Brush Accessory Bit.
An end-shaped brush with carbon steel wire bristles.
Ideal for cleaning flat surfaces and removing rust and corrosion from items made of brass, copper, or other soft ferrous metals such as tools, door knobs, automobile parts, and electrical contacts.
Remove buildup from faucets, clean camp stove burners and more!
You can also use wire brushes to create an artistic effect on coarse-grained wood.
Its size and shape it well suited for getting into hard-to-reach places like slots.